1. Technical Field
The present invention relates to the field of computer systems and transfer of data between a client and server on a distributive network. More particularly, the present invention relates to client sided mapping to a client server. Still more particularly, the present invention relates to a method and system for utilizing client sided mapping for server redundancy and data backup redundancy.
2. Description of Related Art
In a data processing system, a backup/restore subsystem, usually referred to as backup subsystem, is typically used as a means to save a recent copy or version of a file, plus some number of earlier versions of the same file, on some form of backup storage devices, such as magnetic disk drives, tapes, or optical storage devices. The backup subsystem is used as a means of protecting against loss of data in a given data processing system.
For example, if an online version of a file is destroyed or corrupted because of power failure, hardware or software error, user error, or some other type of problem, the latest version of that file which is stored in a backup subsystem can be restored and, therefore, the risk of loss of data is minimized. Another important use of backup subsystems is that, even if failures do not occur but files or data are deleted or changed (either accidentally or intentionally), those files or data can be restored to their earlier state, thus minimizing the loss of data. Therefore, it is readily apparent that backup subsystems are and will remain an important part of the field of data processing.
Installable File System (IFS) technology provides for IFS drivers which map user requests to a specific drive location. For instance, IFS can be used to create a mapped drive on the local client machine at or near boot time. IFS drivers are commonly used to map local drives such as CD-ROM drives and partitioned hard drives. The application alerts the operating system by virtue of the xe2x80x9cdxe2x80x9d drive letter that an IFS driver will be invoked and the xe2x80x9ccdromxe2x80x9d specifies the owner/controller IFS of the CD-ROM drive. An error occurs when the destination drive which was routed by the d: cdrom IFS driver does not respond.
Problems occur when the supporting server does not respond to a client request for support for a particular application. In the event of a server failure, a redundant backup server may be allocated by the administrator, in which case requests directed to the failed server are routed to the redundant backup server.
Similarly, problems occur when data backup support requested by a client is not responded to by the supporting server. However, rather than the administrator allocating a data backup storage unit at each use, data backup allocation is set at a fixed time, and data backup transfer occurs between client and servers only at low usage times, typically after midnight. The problem of redundancy for data backup is that the storage units and servers which provide a dedicated drive for data backup still require an administrator must take some corrective action drive redundancy. The corrective action involves allocating a redundant data backup storage unit or server and routing all requests directed to the failed storage unit or server to the redundant backup storage unit or server.
A further problem with data backup is that it occurs at low usage times, such as early morning. Therefore, depending on the nature of the failure, the administrator may not have time available to reallocate drives for backing up data within the time required. As a result, no data backup occurs until the next scheduled backup, for example, the next morning.
The present invention discloses a method and system for providing drive redundancy and backup using IFS drivers. A file request is received by the operating system, and the appropriate IFS driver for the file is called. The IFS driver remaps the drive path based on a drive location list contained in a file redirection table in the IFS driver. Simultaneously broadcasting writes to each drive on the drive location list ensures drive or server redundancy. Redundancy is ensured for read operations by sequentially traversing the drive location list in the event of a non-responsive drive or server.